Both side of the coin have been discussed here many times with about equal results as far as which is best.
Myself, I prefer the flatter shooting, higher velocity 300gr HPs while others have had good luck with the old tried & true slower 405gr lead bullets.
Some say the meat damage of the HPs is a concern, I disagree.
I have shot deer with both loads and can tell you that each shot is it's own thing from little damage with both to more severe with both.
In all honesty, a little meat loss is better than a complete animal loss.
With carefull trimming at cut up time, I have never lost more than a half of a shoulder on a very small doe, and that was on a double shoulder shot with the 405 lead bullet.
Could have been a 300HP and the end result most likely would have been the same.
Unless it is a large deer you don't really lose that much meat, 2 to 3 hamburgers.
I tend to shoot smaller, younger deer and even then it isn't more than a couple of handsfull of meat.
My 22" Handi is accurate enough that I can take a head or neck shot out to 100 or a little more with very little damage.
On longer shots, out to about 300 to 350 (the longest shot I have taken on a deer with a 45/70) I go either for the vitals or the shoulders.
Depends on the terrain & the angle of the deer at the time.
When it comes down to it, it all depends on what YOUR gun likes best.
All of my 45/70s seem to prefer the Winchester 300gr HPs the best so that is what I use.
Yours may be different.
Get a box of each and see for yourself.
Both will do the job !
LONGTOM